1. Field of the Invention
The present invention relates to a photographic camera having a variable focus lens and having both manual and automatic focusing means in general, and to such cameras wherein said lens must be moved outside of its normal focusing range for the proper functioning of said automatic focusing means, in particular.
2. Description of the Prior Art
One type of photographic camera having both manual and automatic focus control of a variable focus lens is described in U.S. Patent application Ser. No. 838,585 by PIZZUTI et al. The automatic focus control system described in the said PIZZUTI et al application is of the unidirectional type in that movement of the variable focus lens in such a camera to focus on a subject to be photographed is in one direction only. A detailed description of a unidirectional automatic focus control system for use in the control system of the said PIZZUTI et al application is described in some detail in U.S. Patent application Ser. No. 865,852 by SHENK.
The variable focus lens unidirectional automatic focus control system described in the said SHENK application is of the type that is dependent upon the movement of said lens at least a minimum distance outside of its normal focusing range and the actuation of swtich means by such movement, for proper automatic focus control system operation.
A problem associated with a photographic camera having both manual focus control and an automatic focus control system of the type described in the above-cited SHENK application is the lack of a lens movement limiting stop that will enable a camera operator to tactually determine where the normal focusing range limit is located at that end of said focusing range where a lens movement limiting stop has been omitted to make it possible to utilize the unidirectional automatic focus control system mentioned above.
Even though most manually focusable cameras have subject distance indicia located on the lens mount or bezel as a focusing aid, especially in those cameras without a coupled rangefinder, most camera operators will tactually determine that the lens is focused at one end of its focusing range (normally the lens infinity position) by manually moving the lens into a mechanical stop that would normally be located at said infinity end of its focusing range without looking at the distance indicia on the lens bezel to confirm that the lens was actually moved to its said infinity position, particularly when the camera operator has a limited amount of time in which to photograph a subject. If this type of manual focusing procedure was utilized in a camera having manual focus control and a unidirectional focus control system of the type described in the above-mentioned SHENK application, the lens could be moved outside of its normal focusing range and an out-of-focus picture would result if a picture was taken with the lens so positioned.